Sheet glass color tube face panel with pleated skirt

ABSTRACT

A color television picture tube panel is fabricated of relatively thin sheet glass formed to define a substantially rectangular faceplate area surrounded by an upstanding flange having a fluted configuration over portions of its periphery. The end surface of the flange defines a seal edge for forming a glass-to-glass seal with a funnel having a seal edge of sufficient area to bridge the maximum peak to trough dimensions of the fluted portions. Methods of manufacturing such a panel are also described.

United States Patent 1 [111 3,912,104 Schwartz Oct. 14, 1975 [54] SHEETGLASS COLOR TUBE FACE PANEL 3,071,280 l/1963 Mayhew et a1. 220/21 A WITHPLEATED SKIRT 3,322,522 5/1967 Meiresonne 65/44 X 75 l w Sch G] i 13,490,636 l/1970 Nienhuis et al .1 178/7.8 X

t rt l 1 or James Z FOREIGN PATENTS OR APPLICATIONS [73] Asslgnee: 3chug", 770,097 3 1957 United Kingdom 65/107 [22] Filed: Jan. 28, 1974Primary ExaminerWilliam 1. Price Assistant Examiner-Stephen Marcus [211App! 437097 Attorney, Agent, or Firm.lohn H. Coult Related US.Application Data [62] Division of Ser. No. 226,880, Feb. 16, 1972, Pat.No. [57] ABSTRACT 3,825,413, A color television picture tube panel isfabricated of relatively thin sheet glass formed to define a substan-[52] US. Cl 220/2.l A; l78/7.82 i l y r c ngul r faceplate areasurrounded by an up- [51] Int. CL HOlJ 5/02 n ing flange having a flu edconfiguration over por- [58] Field of Search 178/7.8, 7.86, 7.81, 7.82;tions of its periphery. The end surface of the flange 220/2,1 A, 23 A,2,] R, 2,3 R; 65/44, 107 defines a seal edge for forming aglass-to-glass seal with a funnel having a seal edge of sufficient areato [56] R fere Cit d bridge the maximum peak to trough dimensions of theUNITED STATES PATENTS fluted portions. Methods Of manufacturing SUCh 212,878,623 3/1959 Vincent 220/2.1 A panel are also descnbed' 2,969,162 11961 Stutske 220/2.1 A 4 Claims, 3 Drawing Figures Oct. 14, 1975 U.S.Patent SHEET GLASS COLOR TUBE FACE PANEL WITH PLEATED SKIRT RELATEDAPPLICATION This application is a division of application Ser. No.226,880, filed Feb. 16, 1972, now U.S. Pat. No. 3,825,413, issued July23, 1974, and assigned to the assignee of this application.

BACKGROUND OF THE INVENTION This invention relates in general to colortelevision picture tubes and in particular to glass envelopes for colortelevision picture tubes.

The necessity of forming a phosphor mosaic image screen on the innersurface of the picture tube faceplate, which is capable of producinglight of three primary colors responsive to selective excitation,dictates utilization of picture tube envelopes which are separable. Thepicture tube envelope consists of a panel or front section and a funnelor back section. The panel typically has an upstanding flange or skirt,which is useful for strengthening the panel, holding fluids used inscreening and manufacturing, providing a seal edge, and for supporting ashadowing electrode in predetermined relationship to the image screen.In conventional tri-gun picture tubes available today, the shadow masksupport consists of a plurality of inwardly directed studs embedded inthe panel skirt. The shadowing electrode is removable from the mountingstuds since, during normal screening operations, it must be inserted andremoved a number of times. The need for a separable panel portion, therequirement of supporting a relatively heavy shadowing electrode and thenecessity of withstanding high processing temperatures has resulted inthe panel being made of exceptionally thick glass. As a result, theglass envelope represents the major cost in manufacturing a colortelevision picture tube. The heavy thick glass panel imposes otherrestrictions on manufacturing since the various heating cycles must beprogrammed (in both heating and cooling phases) to preclude excessivestress buildup. In practice, substantial time is required for thegradual heat up and cool down cycles. With a panel of thinner glass, thetime required for heating cycles may be reduced and manufacturingeconomies effected.

SUMMARY OF THE INVENTION In accordance with the invention, themassiveness of the glass panel may be greatly reduced withoutdegradation of its strength characteristics. This is achieved by makingthe panel with an upstanding partially fluted flange surrounding thefaceplate area. The fluted portions are readily formed in the upstandingflange or skirt in a simplified panel manufacturing technique andprovide desirable strengthening of the panel member. The resultantpanel, while being lighter, retains the requisite resistance todeformation during high processing temperatures encountered in colortube manufactur- The seal edge or mating surface of the panel is formedby grinding or trimming, since it must be relatively flat for fritsealing with the funnel member. The seal edge, however, includeswavelike portions in the panel corners, which requires the seal edge ofthe funnel to be sufficiently large to bridge the maximum peak to troughdimensions of the flutes.

The fact that a panel configuration including fluted corners may be usedin conjunction with an appropriate funnel allows the panel to befabricated from sheet glass. Consequently, the fluted constructionenables manufacturing economies as well as structural economies.

Accordingly, a principal object of this invention is to provide a panelfor a color cathode ray tube requiring substantially less material thanprior art panels.

A further object of this invention is to provide an economical panel fora color cathode ray tube characterized by fluted portions in the panelskirt.

Another object of this invention is to provide a panel for a colorcathode ray tube which is manufactured from sheet glass material formedwith fluted strengthening portions in the skirt.

Other objects and advantages of this invention will become apparent uponreading the following description in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 represents a glass envelopeincluding a partially cutaway panel section constructed in accordancewith the invention and a mating funnel section.

FIG. 2 represents an enlarged partial view of the inside of the panel ofFIG. 1 taken along the lines 22.

FIG. 3 represents a partial enlarged view of the funnel of FIG. 1 takenalong the lines 3-3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I, a clearglass panel 10 includes an upstanding flange or skirt l1 terminating ina seal edge 13. Each corner of the panel includes a fluted portion 12although such portions need not be restricted to the corners only.Mounted about the interior of the panel on the inside of the upstandingflange is a plurality of mounting studs 15 for supporting a conventionalaper ture type shadow mask (not shown).

Spaced behind panel 10 is a funnel portion 16, including a largebell-shaped portion 17 and a cylindrical neck portion 18 terminating ina slightly flared portion 19. During a stage of manufacture, an electrongun assembly will be inserted into neck 18 and sealed therein. In theprocess, flange 19 will be cut off. Funnel 17 also includes-a seal edge20 for mating engagement with corresponding seal edge 13 of panel 10.Seal edge 20 is flared in the corners as shown at 21 to accommodate thefluted portions of panel 10. Except that funnel 16 includes flaredportions in the corners along the seal edge and that panel I0 is made ofthinner glass and has fluted strengthening portions, the tube envelopeis similar to those presently in use.

FIG. 2 shows a fluted portion of panel 10 in detail. The seal edge inthe fluted portions generally define a sinewave having maximum amplitudeat the diagonals of the panel and diminishing with increasing distanceaway from the diagonals. It is, of course, obvious that the glass fritused in the glass-to-glass sealing step of the final tube manufacture becapable of maintaining the requisite vacuum in the picture tube.Consequently, an enlarged sealing area is provided on the funnel sealedge to embrace the maximum peak to trough dimension of the fluted edge.The critical dimension is that included between 12a and 12b representingthe minimum glass width required to bridge the flute excursions and makean airtight seal. Naturally, because of material and manufacturingtolerances, a larger seal edge than minimum is required, and as shown inFIG. 3, a practical size is one that extends over the full range ofexcursion of the flutes.

FIG. 3 is an enlarged view of the seal edge of the funnel in one cornerwith a dashed line representation of fluted portion 12 of the panelsuperimposed to pictorially show the above relationship of parts. Thefunnel to panel sealing operation may be readily performed by laying abead of frit material on the panel seal edge following the flutedconfiguration. Alternatively, the frit seal may be made by laying a widebead of frit along the funnel seal edge, the frit dimension being largeenough to surround the fluted glass portion of the panel.

A color tube panel in accordance with the invention lends itself todifferent techniques of manufacture also. Practically, a sheet of glassmaterial of required thickness may be sagged over a form which definesthe interior surface of the desired picture tube panel. As the glasssags over the rectangular form, fluted portions or folds will develop inthe corners. After the requisite degree of cooling, the seal edge isformed, preferably by cutting off unwanted material with a high pressureflame. (The seal edge may also be formed by a grinding operation.)Mounting studs 15 may be inserted either as shown in FIG. 2, by locallysoftening the glass in the upstanding flange and pushing the studs intoposition, or by the well-known technique of fritting. lt should beunderstood that the orientation and position of the mounting studs aredetermined by tool mechanisms (not shown) which are independent of minorirregularities in the upstanding flange.

The panel may also be readily vacuum formed or pressed into theappropriate configuration while in the moldable state. The end result ofeach of these techniques is an economically manufactured panel ofrequisite strength but much lighter construction.

The provision of the fluted portions at the corners of the panel isessential to attain sufflcient strength, especially to prevent warpingofthe glass during tube manufacture. In particular, after the mosaicphosphor screen has been deposited using a suitable apertured electrodefor photoexposure any distortion of the panel will upset the criticalrelationship between the aperture mask and the phosphor screen.

For sealing purposes, however, it may be desirable to somewhat compressthe fluted portions while still in the moldable state to reduce themaximum peak to trough dimension mentioned above. In that instance, theseal edge of the funnel need not be flared as much to provide propersealing contact.

The funnel, as shown, includes flared portions in the corners providingthe requisite larger seal edge for mating with the panel flutedportions. Alternatively, the funnel may have an outwardly directed ledgeformed about its periphery for defining a large area seal edge.

What has been described is a novel construction for a color televisionpicture tube envelope. It is recognized that numerous modifications andchanges in the invention may be made without departing from theinvention as set out in the claims.

I claim:

1. A color television picture tube envelope comprising a sheet glasspanel having a seal edge and a mating funnel having a seal edge adaptedto mate with the seal edge of the panel, said panel including a clearfaceplate area circumscribed by an upstanding flange, at least portionsof said flange having folds which extend axially to the panel seal edgeand make sealing engagement with the funnel seal edge.

2. A color television picture tube envelope as set forth in claim 1wherein the folds have a plurality of troughs and peaks, and whereinsaid funnel seal edge is of sufficient area in the region of said foldsto bridge the maximum trough-to-peak dimension of said folds.

3. A color television picture tube envelope as set forth in claim 1wherein said faceplate area is of generally rectangular shape, whereinthe portions of said flange adjacent the sides of the rectangle aresubstantially flat, and wherein said folds are located in each of thecorners of said flange.

4. A color television picture tube envelope as set forth in claim 3wherein said funnel seal edge comprises an outwardly directed ledgeformed in the large end of said funnel which is enlarged in the funnelcorner regions such that the seal edge of the funnel is large enough toembrace the folds at the seal edge in the corners of the panel.

1. A color television picture tube envelope comprising a sheet glasspanel having a seal edge and a mating funnel having a seal edge adaptedto mate with the seal edge of the panel, said panel including a clearfaceplate area circumscribed by an upstanding flange, at least portionsof said flange having folds which extend axially to the panel seal edgeand make sealing engagement with the funnel seal edge.
 2. A colortelevision picture tube envelope as set forth in claim 1 wherein thefolds have a plurality of troughs and peaks, and wherein said funnelseal edge is of sufficient area in the region of said folds to bridgethe maximum trough-to-peak dimension of said folds.
 3. A colortelevision picture tube envelope as set forth in claim 1 wherein saidfaceplate area is of generally rectangular shape, wherein the portionsof said flange adjacent the sides of the rectangle are substantiallyflat, and wherein said folds are located in each of the corners of saidflange.
 4. A color television picture tube envelope as set forth inclaim 3 Wherein said funnel seal edge comprises an outwardly directedledge formed in the large end of said funnel which is enlarged in thefunnel corner regions such that the seal edge of the funnel is largeenough to embrace the folds at the seal edge in the corners of thepanel.